EP0548864B1 - Methode zur Bildung einer schützenden Aluminiumbeschichtung auf einem Kohlenstoff-Kohlenstoff Verbundwerkstoff - Google Patents

Methode zur Bildung einer schützenden Aluminiumbeschichtung auf einem Kohlenstoff-Kohlenstoff Verbundwerkstoff Download PDF

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Publication number
EP0548864B1
EP0548864B1 EP92121672A EP92121672A EP0548864B1 EP 0548864 B1 EP0548864 B1 EP 0548864B1 EP 92121672 A EP92121672 A EP 92121672A EP 92121672 A EP92121672 A EP 92121672A EP 0548864 B1 EP0548864 B1 EP 0548864B1
Authority
EP
European Patent Office
Prior art keywords
carbon
aluminum
coating
slurry
intermetallic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP92121672A
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English (en)
French (fr)
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EP0548864A1 (de
Inventor
Raymond Vincent Sara
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Graftech Technology LLC
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Ucar Carbon Technology Corp
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Filing date
Publication date
Application filed by Ucar Carbon Technology Corp filed Critical Ucar Carbon Technology Corp
Publication of EP0548864A1 publication Critical patent/EP0548864A1/de
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Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
    • C04B41/52—Multiple coating or impregnating multiple coating or impregnating with the same composition or with compositions only differing in the concentration of the constituents, is classified as single coating or impregnation
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
    • C04B41/81—Coating or impregnation
    • C04B41/89—Coating or impregnation for obtaining at least two superposed coatings having different compositions
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C26/00—Coating not provided for in groups C23C2/00 - C23C24/00

Definitions

  • This invention relates to a process for forming an oxidation resistant aluminum coating on a carbon-carbon composite.
  • Carbon-carbon composites are important materials for aerospace and other applications which require high strength and toughness at high temperature.
  • the use of carbon-carbon materials are limited because of their susceptibility to oxidation, particularly at elevated temperatures.
  • Oxidation protection may be provided by coating the carbon-carbon composite with an oxidation resistant metal such as e.g., aluminum.
  • Aluminum is desirable because of its high electrical conductivity, high thermal conductivity and light weight characteristics.
  • a method has been discovered in accordance with the present invention to apply the teachings of the aforementioned patents to a carbon-carbon composite for forming, in situ, a uniform outer layer of aluminum upon a carbon-carbon composite through an intermediary bond of an intermetallic metal carbide interface of tantalum, titanium or hafnium.
  • the method of the present invention for forming an aluminum coating over a carbon-carbon composite in situ comprises the steps of:
  • a conventional carbon-carbon composites is a material composed of a woven or non-woven fabric of carbon fibers with a carbonaceous material directly bonded to the carbon fibers to form a unitary structure.
  • An example of a carbon-carbon composite is a woven fabric of carbon fibers obtained by carbonizing polyacrylonitrile (PAN) fibers, forming a shaped substrate from the carbon fibers and depositing a pyrolytic material such as pyrolytic carbon on the carbon fibers.
  • PAN polyacrylonitrile
  • the deposition of carbon is typically carried out by introducing a hydrocarbon gas into a furnace containing the carbon fiber substrate under conditions permitting the gas to decompose and carbonize at the surface of the carbon fibers.
  • a protective layer of aluminum may be formed, in situ, at the surface of the carbon-carbon composite body by reacting an aluminum intermetallic compound of aluminum and either tantalum, titanium or hafnium with the carbon-carbon composite body in the presence of a critical amount of elemental aluminum preferably disposed upon the surface of the intermetallic compound before it is reacted with the carbon-carbon composite.
  • the preferred aluminum intermetallic is aluminum tantalum which is preferably applied in a liquid suspending vehicle to form a uniform deposit over the carbon-carbon composite. Elemental aluminum must be uniformly distributed upon the surface of the aluminum tantalum intermetallic coating in a concentration of between 0.042 g/cm2 and 0.062 g/cm2 (0.27 g/in2 and 0.4 g/in2).
  • the intermetallic aluminum hafnium or aluminum titanium may be effectively used as a substitute for the aluminum tantalum.
  • the liquid suspending vehicle should comprise a source of carbon, preferably glassy carbon or graphite and a resinous adhesive binder which provides an independent source of carbon upon pyrolytic decomposition.
  • the resin adhesive may be a thermoplastic resin such as a phenolic resin dissolved in alcohol, methyl ethyl ketone or acetone.
  • the pyrolyzing binder should have a char yield of at least 3%.
  • the source of carbon, preferably glassy carbon, is present in the slurry mixture between 1-6% by weight.
  • the composition may also include a conventional anti-settling agent such as MPA 1075 available commercially from NL Chemicals of Hightstown, NJ U.S.A.
  • the liquid suspending vehicle when combined with the aluminum intermetallic compound provides a viscous slurry which may be readily applied to the surface of the carbon-carbon body.
  • the thermoplastic resin provides adhesion to cement the intermetallic compound to the carbon-carbon surface.
  • the intermetallic aluminum compound should be in the form of a power sized between 38 »m and 106 »m (about 150 Tyler mesh and 325 Tyler mesh) or finer.
  • aluminum in its elemental form is dispersed over the coated slurry in a concentration of from 0.042 g/cm2 to 0.062 g/cm2 (.27 g/in2 to .4 g/in2) with an optimum dispersion of 0.0527 g/cm ⁇ 0.0108 g/cm2 (.34 g/in2 ⁇ .07g/in2).
  • the aluminum can be applied as individual particles and sprinkled over the slurry or added through a volatile solvent or as a separately formed slurry in a liquid suspending vehicle such as polyvinyl alcohol, methanol isopropyl alcohol or water.
  • the amount of added aluminum is critical in that too little aluminum will not permit a uniformly adherent aluminum coating to form. Instead the coating will flake off and delaminate upon thermal cycling. Moreover, unless at least 0.042 g/cm2 (.27 g/in2) is added before the slurry is reacted the aluminum coating is too permeable to provide adequate oxidation protection. Conversely, if too much aluminum is added i.e. above 0.062 g/cm2 (0.4 g/in2) aluminum carbide is formed which is hygroscopic and likewise unacceptable for oxidation protection.
  • the coated carbon-carbon composite material is heated in an evacuated furnace preferably in an inert atmosphere at a peak temperature of between 850°C and 1500°C.
  • the intermetallic Al3Ta reacts with the carbon to form an interfacial layer of tantalum carbide and permits the aluminum and aluminum byproduct from the reaction to combine to form a chemically bonded oxidation resistant coating of aluminum which will not peel, flake or delaminate provided elemental aluminum was present within the critical range before the coating is fired.
  • the dried, coated sample was sandwiched between two pieces of 25.4 »m (0.001") thick steel shim stock and isostatically pressed at 103 MPa (15000 psi) for one minute.
  • the sample then was placed on small ZrO2 felt pads placed on a prebaked graphite slab.
  • a dish of getter titanium powder was positioned near the specimen.
  • the retort was evacuated and then purged continuously with oxygen-free argon.
  • the furnace was heated at a rate of 1°C/min to 600°C and then the rate was increased to 6°C/min to 995°C where it was held for six minutes.
  • the Al3Ti/C slurry composition was similar to the one presented in Example 1; the Al3Ta/C slurry composition is as follows: 40.0 g Al3Ta 0.92 g calcined glassy carbon 2.32 g MPA 1075 anti-settling agent 37.74 g 5:1 Methylethylketone:Goodrich cement A-851-B mixture
  • the furnace chamber was evacuated with a mechanical pump before purging with oxygen-free argon. The two were fired simultaneously at a rate of 6°C per minute to 975°C and held for six minutes.
  • the two specimens had uniformly bonded coatings on all sides.
  • the molten aluminum wetted all surfaces thereby creating dense, impermeable coatings which provided excellent oxidation protection.
  • a slurry consisting of 40 g. of 45 »m (325 mesh) Al3Ta, 0.92g calcined glassy carbon, 1.16 g. of MPA-1075 (anti-settling agent), 18.87 g of a 2:1 MEK phenolic resin mixture was homogenized by rolling in a ball mill for one hour. The as received phenolic resin has a char yield of 43.6%. The slurry was then air sprayed onto a 7.62 cm x 7.62 cm x 1.27 cm (3"x 3" x 1/2) plate of ATS graphite. Approximately 1.75 g of aluminum powder was dispersed on top of the dried slurry coating.
  • the coated graphite was fired in a retort furnace to 1005°C using a heating rate of 6°/min. hold time at peak temperature was 34 minutes.
  • the chamber was continuously purged with a O2-free argon at a flow rate of 4 SCFH.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Structural Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Carbon And Carbon Compounds (AREA)
  • Manufacture Of Alloys Or Alloy Compounds (AREA)

Claims (6)

  1. Verfahren zur Bildung einer Aluminiumbeschichtung auf einem Kohlenstoff-Kohlenstoffverbund in-situ, das folgende Schritte umfaßt:
    a) Bilden einer Aufschlämmung aus Teilchen einer intermetallischen Verbindung aus Aluminium und einem aus der aus Tantal, Titan und Hafnium bestehenden Gruppe gewählten Metall in einem flüssigen Trägerbindemittel aus einem harzhaltigen Haftbindemittel, das bei pyrolytischer Zersetzung eine erste Kohlenstoffquelle mit einer minimalen Halbkoksausbeute von 3 % und eine zweite unabhängige Kohlenstoffquelle aus der aus glasartigen Kohlenstoff und Graphit bestehenden Gruppe bereitstellt;
    b) Auftragen der intermetallischen Aufschlämmung mit Aluminium auf den Kohlenstoff-Kohlenstoffverbund zur Bildung einer Beschichtung;
    c) Verteilen von Aluminiumpulver in elementarer Form auf der Oberfläche der Beschichtung in einer Konzentration zwischen 0,042 g/cm² und 0,062 g/cm² (0,27 g/in² und 0,4 g/in²) und
    d) Den Kohlenstoff-Kohlenstoffverbund und die Beschichtung in einem evakuierten, auf zwischen 850 °C und 1500 °C aufgeheizten Ofen für einen kontrollierten Zeitraum zur Bildung einer dichten, undurchlässigen Aluminiumbeschichtung, die chemisch an den Kohlenstoff-Kohlenstoffverbund gebunden ist, reagieren lassen.
  2. Verfahren nach Anspruch 1, wobei das harzhaltige Haftbindemittel in der Aufschlämmung ein in Alkohol, Methylethylketon oder Aceton gelöstes thermoplastisches Harz ist.
  3. Verfahren nach Anspruch 2, wobei das thermoplastische Harz ein Phenolharz ist.
  4. Verfahren nach Anspruch 3, wobei die unabhängige Kohlenstoffquelle glasartigen Kohlenstoff in einer Konzentration zwischen 1 und 6 Gew.-% bezogen auf die Aufschlämmung ist.
  5. Verfahren nach Anspruch 4, wobei das flüssige Trägerbindemittel zusätzlich ein Schwebemittel umfaßt.
  6. Verfahren nach Anspruch 5, wobei die intermetallische Verbindung Al₃Ta ist.
EP92121672A 1991-12-24 1992-12-19 Methode zur Bildung einer schützenden Aluminiumbeschichtung auf einem Kohlenstoff-Kohlenstoff Verbundwerkstoff Expired - Lifetime EP0548864B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US07/813,027 US5413816A (en) 1991-12-24 1991-12-24 Method of forming an aluminum protective coating on a carbon-carbon composite
US813027 1991-12-24

Publications (2)

Publication Number Publication Date
EP0548864A1 EP0548864A1 (de) 1993-06-30
EP0548864B1 true EP0548864B1 (de) 1995-08-23

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EP92121672A Expired - Lifetime EP0548864B1 (de) 1991-12-24 1992-12-19 Methode zur Bildung einer schützenden Aluminiumbeschichtung auf einem Kohlenstoff-Kohlenstoff Verbundwerkstoff

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US (1) US5413816A (de)
EP (1) EP0548864B1 (de)
DE (1) DE69204269T2 (de)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0661248B1 (de) * 1993-12-29 1998-05-27 Across Co., Ltd. Hitzebeständiges Material und Förderband aus diesem Material
EP1341251A1 (de) * 2002-02-28 2003-09-03 OMG AG & Co. KG PEM-Brennstoffzellenstapel
WO2012003228A2 (en) 2010-07-01 2012-01-05 Graftech International Holdings Inc. Graphite electrode
EP2807133A4 (de) 2012-01-26 2016-06-01 Us Gov Sec Navy Feuerfeste metallkeramik und herstellungsverfahren dafür

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4252856A (en) * 1973-03-12 1981-02-24 Union Carbide Corporation Chemically bonded aluminum coated carbon via monocarbides
US4402744A (en) * 1973-03-12 1983-09-06 Union Carbide Corporation Chemically bonded aluminum coating for carbon via monocarbides
CA1045919A (en) * 1973-03-12 1979-01-09 Raymond V. Sara Chemically bonded aluminum coating for carbon via monocarbides
US4347083A (en) * 1973-03-12 1982-08-31 Union Carbide Corporation Chemically bonded aluminum coating for carbon via monocarbides
US4104417A (en) * 1973-03-12 1978-08-01 Union Carbide Corporation Method of chemically bonding aluminum to carbon substrates via monocarbides

Also Published As

Publication number Publication date
DE69204269D1 (de) 1995-09-28
DE69204269T2 (de) 1996-04-04
US5413816A (en) 1995-05-09
EP0548864A1 (de) 1993-06-30

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